Bulky quantum dots exhibit unique optical/electrical properties which no semiconducting materials show. Due to these unique properties, nano quantum dots are becoming of central interest as a material for next-generation high-brightness LEDs, biosensors, lasers, solar cells, etc. Conventionally, quantum dots have been produced mainly in laboratories in such a way to quickly inject cooled precursors into a high-temperature solvent to create nucleuses and then grow the nucleuses under the appropriate temperature conditions. However, the conventional method has limitations in respect to mass production of quantum dots, since it has poor reaction control to make the particle sizes non-uniform and cause great loss in subsequent processes due to reaction conditions depending on the amount of particles, which severely reduces the production amount. Particularly, in the case of quantum dots, the particle size has a direct influence on the optical/electrical properties, uniformity in particle diameter is linked directly with the quality of quantum dots and if the non-uniformity exceeds a predetermined limit, the quantum dots lose their unique qualities and become commercially worthless.
U.S. Pat. No. 6,682,596 discloses a process of producing quantum dots by combining reactants with a solvent and continuously passing the combined solution at a selected flow rate through a thermally conductive reaction tube. However, this conventional method still has a problem in that the sizes of quantum dots become non-uniform when the flow rate increases, which restricts mass production.